From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v2 23/31] arm64: Debugging support Date: Mon, 20 Aug 2012 10:27:44 +0100 Message-ID: <20120820092744.GD25864@mudshark.cambridge.arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <20120816104748.GI31784@mudshark.cambridge.arm.com> <201208161249.35008.arnd@arndb.de> <201208170706.07821.arnd@arndb.de> <20120820090754.GB25864@mudshark.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120820090754.GB25864@mudshark.cambridge.arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Catalin Marinas , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "ulrich.weigand@linaro.org" List-Id: linux-arch.vger.kernel.org On Mon, Aug 20, 2012 at 10:07:54AM +0100, Will Deacon wrote: > On Fri, Aug 17, 2012 at 08:06:07AM +0100, Arnd Bergmann wrote: > > Sorry for the dumb question, but why do you even need PTRACE_GET_THREAD_AREA > > for 64 bit tasks? I thought the thread pointer is a GPR, or is this just > > for compat tasks? > > The TLS is stored in a co-processor register which is read-only for > userspace. I should elaborate: the register is RW for AArch64 tasks, RO for aarch32 tasks (although that doesn't affect the need for the ptrace request). Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:57455 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977Ab2HTJ1x (ORCPT ); Mon, 20 Aug 2012 05:27:53 -0400 Date: Mon, 20 Aug 2012 10:27:44 +0100 From: Will Deacon Subject: Re: [PATCH v2 23/31] arm64: Debugging support Message-ID: <20120820092744.GD25864@mudshark.cambridge.arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <20120816104748.GI31784@mudshark.cambridge.arm.com> <201208161249.35008.arnd@arndb.de> <201208170706.07821.arnd@arndb.de> <20120820090754.GB25864@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120820090754.GB25864@mudshark.cambridge.arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Arnd Bergmann Cc: Catalin Marinas , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "ulrich.weigand@linaro.org" Message-ID: <20120820092744.vOfubHj1F0zmNOvVJqJTiztish76n7hkeloW6GddYOs@z> On Mon, Aug 20, 2012 at 10:07:54AM +0100, Will Deacon wrote: > On Fri, Aug 17, 2012 at 08:06:07AM +0100, Arnd Bergmann wrote: > > Sorry for the dumb question, but why do you even need PTRACE_GET_THREAD_AREA > > for 64 bit tasks? I thought the thread pointer is a GPR, or is this just > > for compat tasks? > > The TLS is stored in a co-processor register which is read-only for > userspace. I should elaborate: the register is RW for AArch64 tasks, RO for aarch32 tasks (although that doesn't affect the need for the ptrace request). Will